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Method for preventing contamination of base plate

a technology for preventing contamination and base plates, applied in the direction of coatings, chemistry apparatus and processes, silicon compounds, etc., can solve the problems of affecting the quality of products, insufficient cleaning of base plates, and countless small scratches

Active Publication Date: 2022-11-22
SHIN ETSU CHEM IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a way to prevent contamination of the base plate used to produce polycrystalline silicon without additional expense. This is done by using an isolation device to separate the space where the base plate is located from other areas.

Problems solved by technology

In particular, contamination of inside (bulk) of polysilicon rods cannot be washed and removed in the following processes unlike surface contamination and thus greatly affects the quality of the products.
However, it is not sufficient to clean the base plate as in JP 6395924 B2.
The base plate has a complicated shape with electrodes, a raw material gas supply port, an exhaust gas port, and the like, and may have countless small scratches due to the collapse or partial drop of the silicon rod.
Thus, it is very difficult to completely remove the dirt from the contaminated base plate and return the base plate to a clean state.
In addition, excessive cleaning may make new scratches on the base plate, which causes dirt to remain.
Furthermore, the cleaning tool itself may be missing and remain on the bale plate, causing contamination.
Furthermore, it is economically difficult to create and maintain a clean room in which a large number of Siemens reactors can be installed.
There is a problem that the effect cannot be immediately obtained for such newly generated contamination.
According to JP 2016-521239 A, the room is cleaned at regular intervals, but there is a problem that the effect cannot be immediately obtained against newly generated contamination as described above.

Method used

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  • Method for preventing contamination of base plate
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  • Method for preventing contamination of base plate

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0075]After the reactor was opened and the polycrystalline silicon rod was harvested spending 1.0 hour, the base plate 8 was protected and isolated from the surrounding space by the isolation device 30 having the support column 33 and the partition 31 made of vinyl. In this case, the isolation time was 6.4 hours (it took 0.1 hours to protect the base plate 8 by the isolation device 30 after harvesting the polycrystalline silicon rod, and it took 0.5 hours to remove the isolation device 30 and re-install the bell jar 4 on the base plate 8). As a result, contamination with metals such as Zn, Ni, and Fe was significantly prevented. In addition, contamination with Ca considered to have been mixed from outside the isolation device 30 was reduced to about ¼. In Example 1, the isolation time occupies 80% (=6.4 / 8.0) of the release time.

example 2

[0076]After the reactor was opened and the polycrystalline silicon rod was harvested spending 1.0 hour, the base plate 8 was protected and isolated from the surrounding space by the isolation device 30 having the support column 33 and the partition 31 made of vinyl. The frequency of ventilation in the space isolated by the FFUs 36 (ULPA filters manufactured by NITTA) attached to the upper part was adjusted to 30 times / h. Metal parts such as the exteriors of the FFUs 36 and the frame of the housing of the isolation device 30 were protected with tape as an anti-rust measure at work in an acidic atmosphere. This further reduced Ca and Na that were thought to be generated by the worker 90. In Example 2, as in Example 1, the isolation time was 6.4 hours (it took 0.1 hours to protect the base plate 8 by the isolation device 30 after harvesting the polycrystalline silicon rod, and it took 0.5 hours to remove the isolation device 30 and re-install the bell jar 4 on the base plate 8).

example 3

[0077]After the reactor was opened and the polycrystalline silicon rod was harvested spending 1.0 hour, the base plate 8 was protected and isolated from the surrounding space by the isolation device 30 having the support column 33 and the partition 31 made of vinyl. The frequency of ventilation in the space isolated by the FFUs 36 attached to the upper part was adjusted to 90 times / h. This further reduced Na and Ca that were thought to be generated by the worker 90. In Example 3, as in Examples 1 and 2, the isolation time was 6.4 hours (it took 0.1 hours to protect the base plate 8 by the isolation device 30 after harvesting the polycrystalline silicon rod, and it took 0.5 hours to remove the isolation device 30 and re-install the bell jar 4 on the base plate 8).

[0078]The results of Comparative Example 1 and Examples 1 to 3 are shown in the table below.

[0079]

TABLE 1Unit: pptwElementNaCrFeNiCuZnCaComparative Example 13971228452392335Example 13032327130641Example 212018902203Example 3...

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Abstract

A method for preventing contamination of a base plate having a step of, after producing polycrystalline silicon in a reactor having the base plate and a lid covering the base plate, removing the lid from the base plate; and a step of isolating space including the base plate by an isolation device.

Description

BACKGROUNDTechnical Field[0001]The present invention relates to a method for preventing contamination of a base plate to be used for producing polycrystalline silicon.[0002]The present application claims the priority of Japanese Patent Application No. 2020-041075 filed on Mar. 10, 2020, the contents of which are entirely incorporated by reference.Related Art[0003]Polycrystalline silicon is a raw material for single crystal silicon for semiconductor manufacturing and silicon for solar cell manufacturing. Siemens method is known as a method for producing polycrystalline silicon. By this method, generally, a silane-based raw material gas is brought into contact with a heated silicon core wire to deposit polycrystalline silicon on the surface of the silicon core wire by chemical vapor deposition (CVD).[0004]The reactor used in Siemens method generally consists of a bell-shaped lid called bell jar and a bottom part called a base plate provided with an electrode, a raw material gas supply...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C23C16/44C23C16/24C01B33/035
CPCC23C16/4401C01B33/035C23C16/24Y02E10/546B08B17/02B08B5/02
Inventor OKADA, TETSUROHOSHINO, NARUHIROISHIDA, MASAHIKO
Owner SHIN ETSU CHEM IND CO LTD